Almond

Almond Kernel Shrivel

Pathogens: Peach yellow leafroll phytoplasma

SYMPTOMS
AND SIGNS

Trees affected by almond kernel shrivel bloom
later than healthy trees, new shoot growth is stunted, and leaves are pale and
smaller than normal. Trees develop thin canopies and the kernels of all nuts
are shriveled at harvest.

COMMENTS
ON THE DISEASE

Almond kernel shrivel has occurred in
certain locations of the northern San Joaquin Valley on almond trees planted on
peach rootstock. It is caused by the Peach yellow leafroll phytoplasma
and is known to affect almond scions grown on peach rootstock. Peach yellow
leafroll phytoplasma can be transmitted by certain insect vectors, and it
is presumed that diseased almond trees are infected in this manner. The
phytoplasma can also be transmitted in infected budwood.

MANAGEMENT

At the present time, the only management
recommendations for almond kernel shrivel are to remove diseased trees and use
planting material produced using budwood sources known to be free of the
disease.

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